All-internal compression inlets for supersonic aircraft, with variable
geometry systems and shock stability bleed systems provide high performance, large
operability margins, i.e. terminal shock stability that reduces the probability
of inlet unstart, and contribute little or nothing to the overall sonic boom signature
of the aircraft. These inlets have very high internal area contraction or compression
and very low external surface angles. All shocks from the internal inlet surfaces
are captured and reflected inside the inlet duct, and all of the external nacelle
surfaces are substantially aligned with the external airflow. The inlet shock stability
system consists of bleed regions that duct bleed airflows to variable area exits
with passive or active exit area controls. This reduces the risk of inlet unstarts
by removing airflow through a large open throat bleed region to compensate for
reductions in diffuser (engine) corrected airflow demand. Because the stability
bleed is not removed until the inlet terminal shock moves upstream over the bleed
region, the necessary normal shock operability margin is provided without compromising
inlet performance (total pressure recovery, and distortion).